to be horrified.

It was very much a lottery ticket,

which most people didn't want to buy.

The eradication of smallpox is one of the most

significant events in the 20th Century.

For me it would be up there with the moon landing.

You certainly couldn't miss a patient who had got smallpox.

You had these blisters, these lesions all over your skin.

All these pustules were filled with virus.

India, as in the Mughal Empire,

understood the value of variolation

because it saw smallpox as a threat to military power.

But the problem was that it was as risky as it sounds -

you're basically trying to stop a deadly disease by giving somebody

a mild case of the same deadly disease.

Variolation could lead to uncontrolled epidemics.

People knew that this was something

that their children would catch

and they might survive or they might die from it

and so it was part of the cycle of life.

When Jenner inoculated the arm of James Phipps,

a young boy of eight,

with the contents of a cowpox bled from a dairy maid,

it became possible for the first time to protect human beings artificially

against pathogenic organisms.

This really tipped the table in favour of prevention and eradication.

To people in the 1700s, this was totally mind-blowing.

Jenner's idea was a game changer.

What happens in 1948 after the Second World War,

the horrors of the Second World War,

is that the world agrees that a new world order was needed.

What a crazy idea it would be to say that you're going to institute

vaccination throughout the entire world.

The 11th World Health Assembly

approved a resolution in 1958 calling for worldwide smallpox eradication.

The WHO galvanised enthusiasm, they standardised the vaccine,

obtained the resources that they needed internationally.

They really deserve tremendous credit for that.

People running the programme

were going from door to door with pictures

of a child with smallpox and asking people in the community

if they knew anyone who had this disease.

You're tracking, testing, isolating.

It's a strategy which many people have said

will be the only way we can keep on top of Covid-19.

May, 1980.

Two men affix their signatures to an historic document.

National and local health workers played an immense role

in the eradication of smallpox,

whether it's in Africa or in Asia -

often selflessly, because a disease like smallpox was

as threatening to them as Covid-19 is to today's health workers.

It's interesting that we're often so eager to commemorate success in wars,

but that much less is done to celebrate success

in the control of disease.

The eradication of smallpox is one of the most

significant events in the 20th Century.

For me it would be up there with the moon landing.

We've eradicated smallpox.

And because we've eradicated smallpox

we know that we can eradicate other human diseases.

If we all work together to tackle the disease,

to stop it spreading, to protect ourselves,

there is no reason why we can't stop another pandemic

like we stopped smallpox.